/*
** $Id: lauxlib.c,v 1.289.1.1 2017/04/19 17:20:42 roberto Exp $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h
*/

#define lauxlib_c
#define LUA_LIB

#include "lprefix.h"

#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
** This file uses only the official API of Lua.
** Any function declared here could be written as an application function.
*/

#include "lua.h"

#include "lauxlib.h"

/*
** {======================================================
** Traceback
** =======================================================
*/

#define LEVELS1 10 /* size of the first part of the stack */
#define LEVELS2 11 /* size of the second part of the stack */

/*
** search for 'objidx' in table at index -1.
** return 1 + string at top if find a good name.
*/
static int findfield(lua_State* L, int objidx, int level)
{
    if (level == 0 || !lua_istable(L, -1))
        return 0;   /* not found */
    lua_pushnil(L); /* start 'next' loop */
    while (lua_next(L, -2))
    { /* for each pair in table */
        if (lua_type(L, -2) == LUA_TSTRING)
        { /* ignore non-string keys */
            if (lua_rawequal(L, objidx, -1))
            {                  /* found object? */
                lua_pop(L, 1); /* remove value (but keep name) */
                return 1;
            }
            else if (findfield(L, objidx, level - 1))
            {                      /* try recursively */
                lua_remove(L, -2); /* remove table (but keep name) */
                lua_pushliteral(L, ".");
                lua_insert(L, -2); /* place '.' between the two names */
                lua_concat(L, 3);
                return 1;
            }
        }
        lua_pop(L, 1); /* remove value */
    }
    return 0; /* not found */
}

/*
** Search for a name for a function in all loaded modules
*/
static int pushglobalfuncname(lua_State* L, lua_Debug* ar)
{
    int top = lua_gettop(L);
    lua_getinfo(L, "f", ar); /* push function */
    lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    if (findfield(L, top + 1, 2))
    {
        const char* name = lua_tostring(L, -1);
        if (strncmp(name, "_G.", 3) == 0)
        {                                /* name start with '_G.'? */
            lua_pushstring(L, name + 3); /* push name without prefix */
            lua_remove(L, -2);           /* remove original name */
        }
        lua_copy(L, -1, top + 1); /* move name to proper place */
        lua_pop(L, 2);            /* remove pushed values */
        return 1;
    }
    else
    {
        lua_settop(L, top); /* remove function and global table */
        return 0;
    }
}

static void pushfuncname(lua_State* L, lua_Debug* ar)
{
    if (pushglobalfuncname(L, ar))
    { /* try first a global name */
        lua_pushfstring(L, "function '%s'", lua_tostring(L, -1));
        lua_remove(L, -2); /* remove name */
    }
    else if (*ar->namewhat != '\0')                            /* is there a name from code? */
        lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name); /* use it */
    else if (*ar->what == 'm')                                 /* main? */
        lua_pushliteral(L, "main chunk");
    else if (*ar->what != 'C') /* for Lua functions, use <file:line> */
        lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
    else /* nothing left... */
        lua_pushliteral(L, "?");
}

static int lastlevel(lua_State* L)
{
    lua_Debug ar;
    int li = 1, le = 1;
    /* find an upper bound */
    while (lua_getstack(L, le, &ar))
    {
        li = le;
        le *= 2;
    }
    /* do a binary search */
    while (li < le)
    {
        int m = (li + le) / 2;
        if (lua_getstack(L, m, &ar))
            li = m + 1;
        else
            le = m;
    }
    return le - 1;
}

LUALIB_API void luaL_traceback(lua_State* L, lua_State* L1, const char* msg, int level)
{
    lua_Debug ar;
    int top = lua_gettop(L);
    int last = lastlevel(L1);
    int n1 = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1;
    if (msg)
        lua_pushfstring(L, "%s\n", msg);
    luaL_checkstack(L, 10, NULL);
    lua_pushliteral(L, "stack traceback:");
    while (lua_getstack(L1, level++, &ar))
    {
        if (n1-- == 0)
        {                                  /* too many levels? */
            lua_pushliteral(L, "\n\t..."); /* add a '...' */
            level = last - LEVELS2 + 1;    /* and skip to last ones */
        }
        else
        {
            lua_getinfo(L1, "Slnt", &ar);
            lua_pushfstring(L, "\n\t%s:", ar.short_src);
            if (ar.currentline > 0)
                lua_pushfstring(L, "%d:", ar.currentline);
            lua_pushliteral(L, " in ");
            pushfuncname(L, &ar);
            if (ar.istailcall)
                lua_pushliteral(L, "\n\t(...tail calls...)");
            lua_concat(L, lua_gettop(L) - top);
        }
    }
    lua_concat(L, lua_gettop(L) - top);
}

/* }====================================================== */

/*
** {======================================================
** Error-report functions
** =======================================================
*/

LUALIB_API int luaL_argerror(lua_State* L, int arg, const char* extramsg)
{
    lua_Debug ar;
    if (!lua_getstack(L, 0, &ar)) /* no stack frame? */
        return luaL_error(L, "bad argument #%d (%s)", arg, extramsg);
    lua_getinfo(L, "n", &ar);
    if (strcmp(ar.namewhat, "method") == 0)
    {
        arg--;        /* do not count 'self' */
        if (arg == 0) /* error is in the self argument itself? */
            return luaL_error(L, "calling '%s' on bad self (%s)", ar.name, extramsg);
    }
    if (ar.name == NULL)
        ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
    return luaL_error(L, "bad argument #%d to '%s' (%s)", arg, ar.name, extramsg);
}

static int typeerror(lua_State* L, int arg, const char* tname)
{
    const char* msg;
    const char* typearg; /* name for the type of the actual argument */
    if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING)
        typearg = lua_tostring(L, -1); /* use the given type name */
    else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA)
        typearg = "light userdata"; /* special name for messages */
    else
        typearg = luaL_typename(L, arg); /* standard name */
    msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg);
    return luaL_argerror(L, arg, msg);
}

static void tag_error(lua_State* L, int arg, int tag) { typeerror(L, arg, lua_typename(L, tag)); }

/*
** The use of 'lua_pushfstring' ensures this function does not
** need reserved stack space when called.
*/
LUALIB_API void luaL_where(lua_State* L, int level)
{
    lua_Debug ar;
    if (lua_getstack(L, level, &ar))
    {                              /* check function at level */
        lua_getinfo(L, "Sl", &ar); /* get info about it */
        if (ar.currentline > 0)
        { /* is there info? */
            lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
            return;
        }
    }
    lua_pushfstring(L, ""); /* else, no information available... */
}

/*
** Again, the use of 'lua_pushvfstring' ensures this function does
** not need reserved stack space when called. (At worst, it generates
** an error with "stack overflow" instead of the given message.)
*/
LUALIB_API int luaL_error(lua_State* L, const char* fmt, ...)
{
    va_list argp;
    va_start(argp, fmt);
    luaL_where(L, 1);
    lua_pushvfstring(L, fmt, argp);
    va_end(argp);
    lua_concat(L, 2);
    return lua_error(L);
}

LUALIB_API int luaL_fileresult(lua_State* L, int stat, const char* fname)
{
    int en = errno; /* calls to Lua API may change this value */
    if (stat)
    {
        lua_pushboolean(L, 1);
        return 1;
    }
    else
    {
        lua_pushnil(L);
        if (fname)
            lua_pushfstring(L, "%s: %s", fname, strerror(en));
        else
            lua_pushstring(L, strerror(en));
        lua_pushinteger(L, en);
        return 3;
    }
}

#if !defined(l_inspectstat) /* { */

#if defined(LUA_USE_POSIX)

#include <sys/wait.h>

/*
** use appropriate macros to interpret 'pclose' return status
*/
#define l_inspectstat(stat, what) \
    if (WIFEXITED(stat))          \
    {                             \
        stat = WEXITSTATUS(stat); \
    }                             \
    else if (WIFSIGNALED(stat))   \
    {                             \
        stat = WTERMSIG(stat);    \
        what = "signal";          \
    }

#else

#define l_inspectstat(stat, what) /* no op */

#endif

#endif /* } */

LUALIB_API int luaL_execresult(lua_State* L, int stat)
{
    const char* what = "exit"; /* type of termination */
    if (stat == -1)            /* error? */
        return luaL_fileresult(L, 0, NULL);
    else
    {
        l_inspectstat(stat, what);     /* interpret result */
        if (*what == 'e' && stat == 0) /* successful termination? */
            lua_pushboolean(L, 1);
        else
            lua_pushnil(L);
        lua_pushstring(L, what);
        lua_pushinteger(L, stat);
        return 3; /* return true/nil,what,code */
    }
}

/* }====================================================== */

/*
** {======================================================
** Userdata's metatable manipulation
** =======================================================
*/

LUALIB_API int luaL_newmetatable(lua_State* L, const char* tname)
{
    if (luaL_getmetatable(L, tname) != LUA_TNIL) /* name already in use? */
        return 0;                                /* leave previous value on top, but return 0 */
    lua_pop(L, 1);
    lua_createtable(L, 0, 2); /* create metatable */
    lua_pushstring(L, tname);
    lua_setfield(L, -2, "__name"); /* metatable.__name = tname */
    lua_pushvalue(L, -1);
    lua_setfield(L, LUA_REGISTRYINDEX, tname); /* registry.name = metatable */
    return 1;
}

LUALIB_API void luaL_setmetatable(lua_State* L, const char* tname)
{
    luaL_getmetatable(L, tname);
    lua_setmetatable(L, -2);
}

LUALIB_API void* luaL_testudata(lua_State* L, int ud, const char* tname)
{
    void* p = lua_touserdata(L, ud);
    if (p != NULL)
    { /* value is a userdata? */
        if (lua_getmetatable(L, ud))
        {                                 /* does it have a metatable? */
            luaL_getmetatable(L, tname);  /* get correct metatable */
            if (!lua_rawequal(L, -1, -2)) /* not the same? */
                p = NULL;                 /* value is a userdata with wrong metatable */
            lua_pop(L, 2);                /* remove both metatables */
            return p;
        }
    }
    return NULL; /* value is not a userdata with a metatable */
}

LUALIB_API void* luaL_checkudata(lua_State* L, int ud, const char* tname)
{
    void* p = luaL_testudata(L, ud, tname);
    if (p == NULL)
        typeerror(L, ud, tname);
    return p;
}

/* }====================================================== */

/*
** {======================================================
** Argument check functions
** =======================================================
*/

LUALIB_API int luaL_checkoption(lua_State* L, int arg, const char* def, const char* const lst[])
{
    const char* name = (def) ? luaL_optstring(L, arg, def) : luaL_checkstring(L, arg);
    int i;
    for (i = 0; lst[i]; i++)
        if (strcmp(lst[i], name) == 0)
            return i;
    return luaL_argerror(L, arg, lua_pushfstring(L, "invalid option '%s'", name));
}

/*
** Ensures the stack has at least 'space' extra slots, raising an error
** if it cannot fulfill the request. (The error handling needs a few
** extra slots to format the error message. In case of an error without
** this extra space, Lua will generate the same 'stack overflow' error,
** but without 'msg'.)
*/
LUALIB_API void luaL_checkstack(lua_State* L, int space, const char* msg)
{
    if (!lua_checkstack(L, space))
    {
        if (msg)
            luaL_error(L, "stack overflow (%s)", msg);
        else
            luaL_error(L, "stack overflow");
    }
}

LUALIB_API void luaL_checktype(lua_State* L, int arg, int t)
{
    if (lua_type(L, arg) != t)
        tag_error(L, arg, t);
}

LUALIB_API void luaL_checkany(lua_State* L, int arg)
{
    if (lua_type(L, arg) == LUA_TNONE)
        luaL_argerror(L, arg, "value expected");
}

LUALIB_API const char* luaL_checklstring(lua_State* L, int arg, size_t* len)
{
    const char* s = lua_tolstring(L, arg, len);
    if (!s)
        tag_error(L, arg, LUA_TSTRING);
    return s;
}

LUALIB_API const char* luaL_optlstring(lua_State* L, int arg, const char* def, size_t* len)
{
    if (lua_isnoneornil(L, arg))
    {
        if (len)
            *len = (def ? strlen(def) : 0);
        return def;
    }
    else
        return luaL_checklstring(L, arg, len);
}

LUALIB_API lua_Number luaL_checknumber(lua_State* L, int arg)
{
    int isnum;
    lua_Number d = lua_tonumberx(L, arg, &isnum);
    if (!isnum)
        tag_error(L, arg, LUA_TNUMBER);
    return d;
}

LUALIB_API lua_Number luaL_optnumber(lua_State* L, int arg, lua_Number def) { return luaL_opt(L, luaL_checknumber, arg, def); }

static void interror(lua_State* L, int arg)
{
    if (lua_isnumber(L, arg))
        luaL_argerror(L, arg, "number has no integer representation");
    else
        tag_error(L, arg, LUA_TNUMBER);
}

LUALIB_API lua_Integer luaL_checkinteger(lua_State* L, int arg)
{
    int isnum;
    lua_Integer d = lua_tointegerx(L, arg, &isnum);
    if (!isnum)
    {
        interror(L, arg);
    }
    return d;
}

LUALIB_API lua_Integer luaL_optinteger(lua_State* L, int arg, lua_Integer def) { return luaL_opt(L, luaL_checkinteger, arg, def); }

/* }====================================================== */

/*
** {======================================================
** Generic Buffer manipulation
** =======================================================
*/

/* userdata to box arbitrary data */
typedef struct UBox
{
    void* box;
    size_t bsize;
} UBox;

static void* resizebox(lua_State* L, int idx, size_t newsize)
{
    void* ud;
    lua_Alloc allocf = lua_getallocf(L, &ud);
    UBox* box = (UBox*)lua_touserdata(L, idx);
    void* temp = allocf(ud, box->box, box->bsize, newsize);
    if (temp == NULL && newsize > 0)
    {                         /* allocation error? */
        resizebox(L, idx, 0); /* free buffer */
        luaL_error(L, "not enough memory for buffer allocation");
    }
    box->box = temp;
    box->bsize = newsize;
    return temp;
}

static int boxgc(lua_State* L)
{
    resizebox(L, 1, 0);
    return 0;
}

static void* newbox(lua_State* L, size_t newsize)
{
    UBox* box = (UBox*)lua_newuserdata(L, sizeof(UBox));
    box->box = NULL;
    box->bsize = 0;
    if (luaL_newmetatable(L, "LUABOX"))
    { /* creating metatable? */
        lua_pushcfunction(L, boxgc);
        lua_setfield(L, -2, "__gc"); /* metatable.__gc = boxgc */
    }
    lua_setmetatable(L, -2);
    return resizebox(L, -1, newsize);
}

/*
** check whether buffer is using a userdata on the stack as a temporary
** buffer
*/
#define buffonstack(B) ((B)->b != (B)->initb)

/*
** returns a pointer to a free area with at least 'sz' bytes
*/
LUALIB_API char* luaL_prepbuffsize(luaL_Buffer* B, size_t sz)
{
    lua_State* L = B->L;
    if (B->size - B->n < sz)
    { /* not enough space? */
        char* newbuff;
        size_t newsize = B->size * 2; /* double buffer size */
        if (newsize - B->n < sz)      /* not big enough? */
            newsize = B->n + sz;
        if (newsize < B->n || newsize - B->n < sz)
            luaL_error(L, "buffer too large");
        /* create larger buffer */
        if (buffonstack(B))
            newbuff = (char*)resizebox(L, -1, newsize);
        else
        { /* no buffer yet */
            newbuff = (char*)newbox(L, newsize);
            memcpy(newbuff, B->b, B->n * sizeof(char)); /* copy original content */
        }
        B->b = newbuff;
        B->size = newsize;
    }
    return &B->b[B->n];
}

LUALIB_API void luaL_addlstring(luaL_Buffer* B, const char* s, size_t l)
{
    if (l > 0)
    { /* avoid 'memcpy' when 's' can be NULL */
        char* b = luaL_prepbuffsize(B, l);
        memcpy(b, s, l * sizeof(char));
        luaL_addsize(B, l);
    }
}

LUALIB_API void luaL_addstring(luaL_Buffer* B, const char* s) { luaL_addlstring(B, s, strlen(s)); }

LUALIB_API void luaL_pushresult(luaL_Buffer* B)
{
    lua_State* L = B->L;
    lua_pushlstring(L, B->b, B->n);
    if (buffonstack(B))
    {
        resizebox(L, -2, 0); /* delete old buffer */
        lua_remove(L, -2);   /* remove its header from the stack */
    }
}

LUALIB_API void luaL_pushresultsize(luaL_Buffer* B, size_t sz)
{
    luaL_addsize(B, sz);
    luaL_pushresult(B);
}

LUALIB_API void luaL_addvalue(luaL_Buffer* B)
{
    lua_State* L = B->L;
    size_t l;
    const char* s = lua_tolstring(L, -1, &l);
    if (buffonstack(B))
        lua_insert(L, -2); /* put value below buffer */
    luaL_addlstring(B, s, l);
    lua_remove(L, (buffonstack(B)) ? -2 : -1); /* remove value */
}

LUALIB_API void luaL_buffinit(lua_State* L, luaL_Buffer* B)
{
    B->L = L;
    B->b = B->initb;
    B->n = 0;
    B->size = LUAL_BUFFERSIZE;
}

LUALIB_API char* luaL_buffinitsize(lua_State* L, luaL_Buffer* B, size_t sz)
{
    luaL_buffinit(L, B);
    return luaL_prepbuffsize(B, sz);
}

/* }====================================================== */

/*
** {======================================================
** Reference system
** =======================================================
*/

/* index of free-list header */
#define freelist 0

LUALIB_API int luaL_ref(lua_State* L, int t)
{
    int ref;
    if (lua_isnil(L, -1))
    {
        lua_pop(L, 1);     /* remove from stack */
        return LUA_REFNIL; /* 'nil' has a unique fixed reference */
    }
    t = lua_absindex(L, t);
    lua_rawgeti(L, t, freelist);     /* get first free element */
    ref = (int)lua_tointeger(L, -1); /* ref = t[freelist] */
    lua_pop(L, 1);                   /* remove it from stack */
    if (ref != 0)
    {                                /* any free element? */
        lua_rawgeti(L, t, ref);      /* remove it from list */
        lua_rawseti(L, t, freelist); /* (t[freelist] = t[ref]) */
    }
    else                                 /* no free elements */
        ref = (int)lua_rawlen(L, t) + 1; /* get a new reference */
    lua_rawseti(L, t, ref);
    return ref;
}

LUALIB_API void luaL_unref(lua_State* L, int t, int ref)
{
    if (ref >= 0)
    {
        t = lua_absindex(L, t);
        lua_rawgeti(L, t, freelist);
        lua_rawseti(L, t, ref); /* t[ref] = t[freelist] */
        lua_pushinteger(L, ref);
        lua_rawseti(L, t, freelist); /* t[freelist] = ref */
    }
}

/* }====================================================== */

/*
** {======================================================
** Load functions
** =======================================================
*/

typedef struct LoadF
{
    int n;             /* number of pre-read characters */
    FILE* f;           /* file being read */
    char buff[BUFSIZ]; /* area for reading file */
} LoadF;

static const char* getF(lua_State* L, void* ud, size_t* size)
{
    LoadF* lf = (LoadF*)ud;
    (void)L; /* not used */
    if (lf->n > 0)
    {                  /* are there pre-read characters to be read? */
        *size = lf->n; /* return them (chars already in buffer) */
        lf->n = 0;     /* no more pre-read characters */
    }
    else
    { /* read a block from file */
        /* 'fread' can return > 0 *and* set the EOF flag. If next call to
       'getF' called 'fread', it might still wait for user input.
       The next check avoids this problem. */
        if (feof(lf->f))
            return NULL;
        *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f); /* read block */
    }
    return lf->buff;
}

static int errfile(lua_State* L, const char* what, int fnameindex)
{
    const char* serr = strerror(errno);
    const char* filename = lua_tostring(L, fnameindex) + 1;
    lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
    lua_remove(L, fnameindex);
    return LUA_ERRFILE;
}

static int skipBOM(LoadF* lf)
{
    const char* p = "\xEF\xBB\xBF"; /* UTF-8 BOM mark */
    int c;
    lf->n = 0;
    do
    {
        c = getc(lf->f);
        if (c == EOF || c != *(const unsigned char*)p++)
            return c;
        lf->buff[lf->n++] = c; /* to be read by the parser */
    } while (*p != '\0');
    lf->n = 0;          /* prefix matched; discard it */
    return getc(lf->f); /* return next character */
}

/*
** reads the first character of file 'f' and skips an optional BOM mark
** in its beginning plus its first line if it starts with '#'. Returns
** true if it skipped the first line.  In any case, '*cp' has the
** first "valid" character of the file (after the optional BOM and
** a first-line comment).
*/
static int skipcomment(LoadF* lf, int* cp)
{
    int c = *cp = skipBOM(lf);
    if (c == '#')
    { /* first line is a comment (Unix exec. file)? */
        do
        { /* skip first line */
            c = getc(lf->f);
        } while (c != EOF && c != '\n');
        *cp = getc(lf->f); /* skip end-of-line, if present */
        return 1;          /* there was a comment */
    }
    else
        return 0; /* no comment */
}

LUALIB_API int luaL_loadfilex(lua_State* L, const char* filename, const char* mode)
{
    LoadF lf;
    int status, readstatus;
    int c;
    int fnameindex = lua_gettop(L) + 1; /* index of filename on the stack */
    if (filename == NULL)
    {
        lua_pushliteral(L, "=stdin");
        lf.f = stdin;
    }
    else
    {
        lua_pushfstring(L, "@%s", filename);
        lf.f = fopen(filename, "r");
        if (lf.f == NULL)
            return errfile(L, "open", fnameindex);
    }
    if (skipcomment(&lf, &c))   /* read initial portion */
        lf.buff[lf.n++] = '\n'; /* add line to correct line numbers */
    if (c == LUA_SIGNATURE[0] && filename)
    {                                         /* binary file? */
        lf.f = freopen(filename, "rb", lf.f); /* reopen in binary mode */
        if (lf.f == NULL)
            return errfile(L, "reopen", fnameindex);
        skipcomment(&lf, &c); /* re-read initial portion */
    }
    if (c != EOF)
        lf.buff[lf.n++] = c; /* 'c' is the first character of the stream */
    status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
    readstatus = ferror(lf.f);
    if (filename)
        fclose(lf.f); /* close file (even in case of errors) */
    if (readstatus)
    {
        lua_settop(L, fnameindex); /* ignore results from 'lua_load' */
        return errfile(L, "read", fnameindex);
    }
    lua_remove(L, fnameindex);
    return status;
}

typedef struct LoadS
{
    const char* s;
    size_t size;
} LoadS;

static const char* getS(lua_State* L, void* ud, size_t* size)
{
    LoadS* ls = (LoadS*)ud;
    (void)L; /* not used */
    if (ls->size == 0)
        return NULL;
    *size = ls->size;
    ls->size = 0;
    return ls->s;
}

LUALIB_API int luaL_loadbufferx(lua_State* L, const char* buff, size_t size, const char* name, const char* mode)
{
    LoadS ls;
    ls.s = buff;
    ls.size = size;
    return lua_load(L, getS, &ls, name, mode);
}

LUALIB_API int luaL_loadstring(lua_State* L, const char* s) { return luaL_loadbuffer(L, s, strlen(s), s); }

/* }====================================================== */

LUALIB_API int luaL_getmetafield(lua_State* L, int obj, const char* event)
{
    if (!lua_getmetatable(L, obj)) /* no metatable? */
        return LUA_TNIL;
    else
    {
        int tt;
        lua_pushstring(L, event);
        tt = lua_rawget(L, -2);
        if (tt == LUA_TNIL) /* is metafield nil? */
            lua_pop(L, 2);  /* remove metatable and metafield */
        else
            lua_remove(L, -2); /* remove only metatable */
        return tt;             /* return metafield type */
    }
}

LUALIB_API int luaL_callmeta(lua_State* L, int obj, const char* event)
{
    obj = lua_absindex(L, obj);
    if (luaL_getmetafield(L, obj, event) == LUA_TNIL) /* no metafield? */
        return 0;
    lua_pushvalue(L, obj);
    lua_call(L, 1, 1);
    return 1;
}

LUALIB_API lua_Integer luaL_len(lua_State* L, int idx)
{
    lua_Integer l;
    int isnum;
    lua_len(L, idx);
    l = lua_tointegerx(L, -1, &isnum);
    if (!isnum)
        luaL_error(L, "object length is not an integer");
    lua_pop(L, 1); /* remove object */
    return l;
}

LUALIB_API const char* luaL_tolstring(lua_State* L, int idx, size_t* len)
{
    if (luaL_callmeta(L, idx, "__tostring"))
    { /* metafield? */
        if (!lua_isstring(L, -1))
            luaL_error(L, "'__tostring' must return a string");
    }
    else
    {
        switch (lua_type(L, idx))
        {
        case LUA_TNUMBER:
        {
            if (lua_isinteger(L, idx))
                lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx));
            else
                lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx));
            break;
        }
        case LUA_TSTRING:
            lua_pushvalue(L, idx);
            break;
        case LUA_TBOOLEAN:
            lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
            break;
        case LUA_TNIL:
            lua_pushliteral(L, "nil");
            break;
        default:
        {
            int tt = luaL_getmetafield(L, idx, "__name"); /* try name */
            const char* kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : luaL_typename(L, idx);
            lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx));
            if (tt != LUA_TNIL)
                lua_remove(L, -2); /* remove '__name' */
            break;
        }
        }
    }
    return lua_tolstring(L, -1, len);
}

/*
** {======================================================
** Compatibility with 5.1 module functions
** =======================================================
*/
#if defined(LUA_COMPAT_MODULE)

static const char* luaL_findtable(lua_State* L, int idx, const char* fname, int szhint)
{
    const char* e;
    if (idx)
        lua_pushvalue(L, idx);
    do
    {
        e = strchr(fname, '.');
        if (e == NULL)
            e = fname + strlen(fname);
        lua_pushlstring(L, fname, e - fname);
        if (lua_rawget(L, -2) == LUA_TNIL)
        {                                                    /* no such field? */
            lua_pop(L, 1);                                   /* remove this nil */
            lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */
            lua_pushlstring(L, fname, e - fname);
            lua_pushvalue(L, -2);
            lua_settable(L, -4); /* set new table into field */
        }
        else if (!lua_istable(L, -1))
        {                  /* field has a non-table value? */
            lua_pop(L, 2); /* remove table and value */
            return fname;  /* return problematic part of the name */
        }
        lua_remove(L, -2); /* remove previous table */
        fname = e + 1;
    } while (*e == '.');
    return NULL;
}

/*
** Count number of elements in a luaL_Reg list.
*/
static int libsize(const luaL_Reg* l)
{
    int size = 0;
    for (; l && l->name; l++) size++;
    return size;
}

/*
** Find or create a module table with a given name. The function
** first looks at the LOADED table and, if that fails, try a
** global variable with that name. In any case, leaves on the stack
** the module table.
*/
LUALIB_API void luaL_pushmodule(lua_State* L, const char* modname, int sizehint)
{
    luaL_findtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE, 1);
    if (lua_getfield(L, -1, modname) != LUA_TTABLE)
    {                  /* no LOADED[modname]? */
        lua_pop(L, 1); /* remove previous result */
        /* try global variable (and create one if it does not exist) */
        lua_pushglobaltable(L);
        if (luaL_findtable(L, 0, modname, sizehint) != NULL)
            luaL_error(L, "name conflict for module '%s'", modname);
        lua_pushvalue(L, -1);
        lua_setfield(L, -3, modname); /* LOADED[modname] = new table */
    }
    lua_remove(L, -2); /* remove LOADED table */
}

LUALIB_API void luaL_openlib(lua_State* L, const char* libname, const luaL_Reg* l, int nup)
{
    luaL_checkversion(L);
    if (libname)
    {
        luaL_pushmodule(L, libname, libsize(l)); /* get/create library table */
        lua_insert(L, -(nup + 1));               /* move library table to below upvalues */
    }
    if (l)
        luaL_setfuncs(L, l, nup);
    else
        lua_pop(L, nup); /* remove upvalues */
}

#endif
/* }====================================================== */

/*
** set functions from list 'l' into table at top - 'nup'; each
** function gets the 'nup' elements at the top as upvalues.
** Returns with only the table at the stack.
*/
LUALIB_API void luaL_setfuncs(lua_State* L, const luaL_Reg* l, int nup)
{
    luaL_checkstack(L, nup, "too many upvalues");
    for (; l->name != NULL; l++)
    { /* fill the table with given functions */
        int i;
        for (i = 0; i < nup; i++) /* copy upvalues to the top */
            lua_pushvalue(L, -nup);
        lua_pushcclosure(L, l->func, nup); /* closure with those upvalues */
        lua_setfield(L, -(nup + 2), l->name);
    }
    lua_pop(L, nup); /* remove upvalues */
}

/*
** ensure that stack[idx][fname] has a table and push that table
** into the stack
*/
LUALIB_API int luaL_getsubtable(lua_State* L, int idx, const char* fname)
{
    if (lua_getfield(L, idx, fname) == LUA_TTABLE)
        return 1; /* table already there */
    else
    {
        lua_pop(L, 1); /* remove previous result */
        idx = lua_absindex(L, idx);
        lua_newtable(L);
        lua_pushvalue(L, -1);        /* copy to be left at top */
        lua_setfield(L, idx, fname); /* assign new table to field */
        return 0;                    /* false, because did not find table there */
    }
}

/*
** Stripped-down 'require': After checking "loaded" table, calls 'openf'
** to open a module, registers the result in 'package.loaded' table and,
** if 'glb' is true, also registers the result in the global table.
** Leaves resulting module on the top.
*/
LUALIB_API void luaL_requiref(lua_State* L, const char* modname, lua_CFunction openf, int glb)
{
    luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    lua_getfield(L, -1, modname); /* LOADED[modname] */
    if (!lua_toboolean(L, -1))
    {                  /* package not already loaded? */
        lua_pop(L, 1); /* remove field */
        lua_pushcfunction(L, openf);
        lua_pushstring(L, modname);   /* argument to open function */
        lua_call(L, 1, 1);            /* call 'openf' to open module */
        lua_pushvalue(L, -1);         /* make copy of module (call result) */
        lua_setfield(L, -3, modname); /* LOADED[modname] = module */
    }
    lua_remove(L, -2); /* remove LOADED table */
    if (glb)
    {
        lua_pushvalue(L, -1);      /* copy of module */
        lua_setglobal(L, modname); /* _G[modname] = module */
    }
}

LUALIB_API const char* luaL_gsub(lua_State* L, const char* s, const char* p, const char* r)
{
    const char* wild;
    size_t l = strlen(p);
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    while ((wild = strstr(s, p)) != NULL)
    {
        luaL_addlstring(&b, s, wild - s); /* push prefix */
        luaL_addstring(&b, r);            /* push replacement in place of pattern */
        s = wild + l;                     /* continue after 'p' */
    }
    luaL_addstring(&b, s); /* push last suffix */
    luaL_pushresult(&b);
    return lua_tostring(L, -1);
}

static void* l_alloc(void* ud, void* ptr, size_t osize, size_t nsize)
{
    (void)ud;
    (void)osize; /* not used */
    if (nsize == 0)
    {
        free(ptr);
        return NULL;
    }
    else
    { /* cannot fail when shrinking a block */
        void* newptr = realloc(ptr, nsize);
        if (newptr == NULL && ptr != NULL && nsize <= osize)
            return ptr;    /* keep the original block */
        else               /* no fail or not shrinking */
            return newptr; /* use the new block */
    }
}

static int panic(lua_State* L)
{
    lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n", lua_tostring(L, -1));
    return 0; /* return to Lua to abort */
}

LUALIB_API lua_State* luaL_newstate(void)
{
    lua_State* L = lua_newstate(l_alloc, NULL);
    if (L)
        lua_atpanic(L, &panic);
    return L;
}

LUALIB_API void luaL_checkversion_(lua_State* L, lua_Number ver, size_t sz)
{
    const lua_Number* v = lua_version(L);
    if (sz != LUAL_NUMSIZES) /* check numeric types */
        luaL_error(L, "core and library have incompatible numeric types");
    if (v != lua_version(NULL))
        luaL_error(L, "multiple Lua VMs detected");
    else if (*v != ver)
        luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f", (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v);
}
